> On 31 Mar 2017, at 19:28, John McKown <john.archie.mck...@gmail.com> wrote: > > On Fri, Mar 31, 2017 at 12:15 PM, Berend Hasselman <b...@xs4all.nl> wrote: > > I have noted a difference between R on macOS en on Kubuntu Trusty (64bits) > with complex division. > I don't know what would happen R on Windows. > > R.3.3.3: > > macOS (10.11.6) > ----------------- > > (1+2i)/0 > [1] NaN+NaNi > > (-1+2i)/0 > [1] NaN+NaNi > > > > 1i/0 > [1] NaN+NaNi > > 1i/(0+0i) > [1] NaN+NaNi > > > KubuntuTrusty > ----------------- > > (1+2i)/0 > [1] Inf+Infi > > (-1+2i)/0 > [1] -Inf+Infi > > > > 1i/0 > [1] NaN+Infi > > 1i/(0+0i) > [1] NaN+Infi > > Interesting to see what R on Windows delivers. > > > (1+2i)/0 > [1] Inf+Infi > > (-1+2i)/0 > [1] -Inf+Infi > > 1i/0 > [1] NaN+Infi > > 1i/(0+0i) > [1] NaN+Infi > > Sys.info() > sysname release > "Windows" "7 x64" > version nodename > "build 7601, Service Pack 1" "IT-JMCKOWN" > machine login > "x86-64" "John.Mckown" > user effective_user > "John.Mckown" "John.Mckown" > > > > Same as Kubuntu. I am _guessing_ that the MacOS somehow sets up the floating > point processing to work differently, since they are all on Intel machines > nowadays. Or the R was customized to detect division by zero in software and > not really do any floating point processing at all. > >
I think it's the system math library that does this. I have assumed that the Kubuntu Trusty (and Windows) give the correct result. In my package geigen I have taken that into account and made a specialized complexdivision function that tries to detect a possibly wrong outcome (which appears to happen only on macOS). Berend Hasselman > Berend Hasselman > > > > -- > "Irrigation of the land with seawater desalinated by fusion power is ancient. > It's called 'rain'." -- Michael McClary, in alt.fusion > > Maranatha! <>< > John McKown ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
